There is a national interest in the discovery of alternative sources of fuels and chemicals, other than from petroleum resources. As the public discussion concerning the availability of petroleum resources and the need for alternative sources continues, government mandates will require transportation fuels to include, at least in part, hydrocarbons derived from sources besides petroleum. As such, there is a need to develop alternative sources for hydrocarbons useful for producing fuels and chemicals.
One possible alternative source of hydrocarbons for producing fuels and chemicals is the natural carbon found in plants and animals, such as for example, oils and fats. These so-called “natural” carbon resources (or renewable hydrocarbons) are widely available, and remain a target alternative source for the production of hydrocarbons. For example, it is known that oils and fats, such as those contained in vegetable oil, can be processed and used as fuel. Biodiesel is one such product and may be produced by subjecting a base biomass-derived oil to a transesterification process using methanol in order to convert the oil to desired methyl esters. After processing, the products produced have very similar combustion properties as compared to petroleum-derived hydrocarbons. However, the use of biodiesel as an alternative fuel has not yet been proven to be cost effective. In addition, biodiesel often exhibits poor cold flow properties, which limits its use in pure form in cold climates.
Unmodified vegetable oils and fats have also been used as additives in diesel fuel to improve the qualities of the diesel fuel, such as for example, the lubricity. However, problems such as injector coking and the degradation of combustion chamber conditions have been associated with these unmodified additives. Since cetane (C16H34), heptadecane (C17H36) and octadecane (C18H38) by definition have very good ignition properties (expressed as cetane rating), it is often desired to add paraffinic hydrocarbons in the C16-C18 range, provided that other properties of the additive (such as for example, viscosity, pour point, cloud point, etc.) are congruent with those of the diesel fuel. Processes for converting biomass-derived oils into hydrocarbons have been achieved, such as, for example, contacting a diesel/vegetable oil mixture with a hydrotreating catalyst. However, triglyceride feeds often contain significant amounts of impurities such as such as phospho-lipids, proteins, gums, and other metal containing compounds (such as alkali metals, alkaline earth metals). These impurities can cause catalyst deactivation and plugging of the hydrotreating reactor catalyst bed as well as fouling of heat exchangers and other process equipment.
As such, development of a new and simple process for removing impurities such as phospho-lipids, proteins, gums, metal containing compounds (such as alkali metals, alkaline earth metals) from such oils would be a significant contribution to the art.